Batteries based on multivalent ions such as Mg²⁺, Ca²⁺, and Al³⁺ can be cheaper and safer alternatives to Lithium-ion batteries (LIBs). However, the development of multivalent-ion batteries has been hindered by the lack of appropriate electrolytes and cathode materials for these new battery chemistries. Understanding the kinetics and thermodynamics of multivalent ion intercalation into structure of materials is essential for designing cathode materials for these systems. Recently, we have reported on high-performance cathode materials for rechargeable aluminum batteries based on two-dimensional (2D) vanadium carbide MXene (V₂C).[1] MXenes are a family of 2D transition metal carbides, nitrides, and/or carbonitrides with a general formula of M_n+1X_n (n=1,2, and 3, M is a transition metal, and X is carbon and/or nitrogen), that are produced by selective etching of the A layer elements (i.e. Al) from MAX phases (i.e. V₂AlC), a large group of layered ternary carbides, nitrides, and carbonitrides.[2] In this presentation, we report our recent findings on kinetics and thermodynamics of Al ion intercalation into MXenes. Using various electroanalytical and spectroscopic techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS) we have shed light on the intercalation mechanism and kinetics of intercalation of Al ions into MXene structures. Our results show that interlayer expansion of MXenes can significantly decrease the diffusion coefficient of ions and improve their performance of the cathode materials. These findings can potentially lead to development of a group of cathode materials for high performance Al-batteries

References

1. VahidMohammadi, A. Hadjikhani, S. Shahbazmohamadi, and M. Beidaghi, Two-Dimensional Vanadium Carbide (MXene) as a High-Capacity Cathode Material for Rechargeable Aluminum Batteries, ACS Nano, 2017, 10.1021/acsnano.7b05350.
2. 2D metal carbides and nitrides (MXenes) for energy storage, B. Anasori, M. R. Lukatskaya, and Y. Gogotsi, Nature Energy, 2017, 10.1038/natrevmats.2016.98.